In some circumstances, a portion of an aircraft's jet engine exhaust plume may contact various portions of the aircraft's surfaces during operation. Such contact may result in localized heating of the contacted surfaces. Depending on the type of aircraft and the location of the engine(s), the contacted surfaces may include portions of the fuselage, control surfaces, and/or wings. Some aircraft utilize thrust reversers that help maneuver the aircraft while on the ground. In some cases, the thrust reversers may direct hot engine exhaust gases over a surface of the aircraft. For instance, thrust reversers on some aircraft may direct hot exhaust gases over a leading edge of the wing. The hot exhaust gases may cause thermal degradation of conventional coatings that may be present on the surface of the aircraft, such as the leading edge of the wing. Thermal degradation of the coating may result in an undesirable appearance of the coating among other deleterious effects.
In aircraft applications, thermal degradation of the coating may be magnified as a result of impacts with high velocity rain drops. Impacts with rain drops during flight may further damage and erode the coating. In cases where the coating is already stressed, such impacts may cause significant damage to the coating including, for example, exposure of the underlying metal.
Exposed metal may be especially problematic in military applications where reduced visibility of the aircraft may be desirable. Many military aircraft may have a camouflage coating that is designed to reduce the visibility of the aircraft. Bare metal may result in a highly reflective surface that may compromise the overall effectiveness of the camouflage coating system.
Commercially available high temperature coatings have been developed that can withstand high temperatures. However many of these coatings may have disadvantages that may make them undesirable for use on aircraft. For instance, some high temperature coatings may have insufficient resistance to the repetitive impact of high velocity rain droplets during flight. In some cases, these coatings may be damaged and fail as a result.
In other cases, the coatings may not readily adhere to the aircraft surface and may require specialized treatments of the surface to be coated. Surface roughening treatments, such as grit blasting, may initially lead to improved coating adhesion, but are typically labor intensive and may be difficult to perform in aircraft paint hangar environments. Aircraft parts with grit blasted surfaces may also be more difficult to strip and re-clean prior to re-painting at some later time. Some coatings may need to be heat cured for the coating to obtain the desired properties. In many cases, it may not be possible to heat cure the coating, this may be especially true in the case of large winged aircraft.
Additionally, some coatings can only be applied by specialized processing equipment in factory environments. In some circumstances, the parts to be coated may need to be removed from the aircraft. Applying such coatings to existing aircraft may not always be feasible because of the high costs that may be associated with such operations and delays that may be introduced into aircraft painting and re-painting operations.
Thus, there still exists a need for a heat and erosion resistant coating that can be applied without extensive pretreatment of the surface to be coated and without heat curing or the use of specialized processing equipment.